pCR most commonly means **pathologic complete response**. It describes **no remaining detectable cancer on pathology** in the treated area after therapy given before surgery. pCR is most often discussed after **neoadjuvant** (pre-surgery) chemotherapy, targeted therapy, immunotherapy, and/or radiation therapy. Clinicians use pCR to help describe treatment response and to support research and treatment planning.

Pathologic complete response is a pathology finding after cancer treatment. It means no remaining cancer is seen in the tissue removed and examined under a microscope. It is most commonly discussed after treatment given before surgery (neoadjuvant therapy). It is used in both routine cancer care and cancer clinical trials.

A Sentinel node is the first lymph node (or small group of nodes) that drains lymph fluid from a specific area of the body. It is commonly used in cancer care to check whether cancer cells have started to spread through the lymphatic system. Clinicians most often discuss the Sentinel node in cancers like breast cancer and melanoma. Testing the Sentinel node can help guide staging and treatment decisions.

Isolated tumor cells are very small clusters or single cancer cells found outside the main tumor. They are most often reported by a pathologist in lymph nodes removed during cancer surgery, especially sentinel lymph nodes. In many cancers, they represent the smallest category of tumor spread that can be detected under the microscope or with special stains. They are commonly used in cancer staging reports to help describe the extent of disease.

Micrometastasis is a very small deposit of cancer cells that has spread from the original (primary) tumor to another location. It is usually too small to be felt on exam or seen on routine imaging. It is most commonly discussed in pathology reports, especially when lymph nodes are examined after surgery. It can influence cancer staging and the way clinicians estimate recurrence risk.

Tumor budding is a pathology finding where single cancer cells or small clusters of cells “break off” at the edge of a tumor. It is seen under the microscope in tissue removed by biopsy or surgery. It is most commonly discussed in colorectal cancer, but it can be reported in several solid tumors. Clinicians use it as a marker of how invasive a tumor may be.

ECE most commonly means **extracapsular extension** in oncology. It describes cancer cells that have **grown through the capsule (outer covering) of a lymph node** into nearby tissue. ECE is usually identified by a **pathologist** when lymph nodes are examined after a biopsy or surgery. Clinicians use ECE in **staging discussions, risk assessment, and treatment planning**, especially in cancers that spread to lymph nodes.

Extracapsular extension is a pathology term describing cancer that has grown through the outer “capsule” of a structure and into nearby tissue. It is most commonly discussed when cancer spreads to a lymph node and then grows beyond the lymph node capsule (also called *extranodal extension* in some cancers). It can also be used in some organ-based cancers when tumor extends beyond an organ’s boundary or capsule. Clinicians use it to better understand how far a cancer has spread and how aggressive it may be.

PNI is an acronym used in oncology, but its meaning depends on the clinical context. Most commonly, PNI refers to **perineural invasion**, a pathology finding where cancer cells are seen around or within nerves. PNI can also mean **prognostic nutritional index**, a calculated score based on blood tests that reflects nutrition and immune status. Both forms of PNI are used in cancer care to help describe risk and guide clinical discussions.

Perineural invasion is a pathology finding where cancer cells are seen tracking along or around a nerve. It is most often identified under the microscope in biopsy or surgery specimens. Clinicians use it as a feature that can help describe how a tumor is behaving locally. It commonly appears in pathology reports for several solid tumors, especially in the head and neck, skin, pancreas, prostate, and colorectal region.